Generator Bearings are One of the Most Common Causes of unplanned maintenance work at a Wind Farm due to Bearing Temperatures Running too High

Martine Jagger details how cleaning grease can help keep wind turbines turning

Increasing environmental concerns, social influence, corporate governance and tighter regulations are encouraging people to seek out alternative energy solutions such as wind power. In fact, according to the Global Wind Council, 2020 was the best year so far for wind energy production, with 93GW of new capacity installed. That’s a 53% year-on-year increase.

As the wind energy industry continues to grow, trouble-free turbine operation is even more crucial to wind plant operators, but the operational demands placed on modern wind turbines are extreme, to say the least! From fluctuations in temperature, through adverse weather, to extreme peak loads, under these harsh conditions, gearboxes and bearings face continuous and intense strain. The size of modern turbines is growing too, from being able to produce just 0.5MW 20 years ago, design improvements mean today’s turbines can deliver more than 13MW, but this is placing more torque and pressure on generators. This can have a significant impact on the reliability of the turbines, which is why lubricants for wind-turbines play a crucial role.

Up to 70% of operational costs are due to unplanned maintenance leading to the loss of power generation, which is an expensive cost to a business. Generator bearings are one of the most common causes of unplanned maintenance work at a wind farm due to bearing temperatures running too high, often in combination with vibrations. These are caused in part due to the design of internal cavities and grease exit ports, which in some turbine generators restrict grease flow. This leads to an excessive build-up of thickener around the outside of the cavity as well as the inner race of bearings. These grease deposits lead to spikes in temperature and vibrations that result in temperature alarms and, eventually turbine shutdowns. In the long term, this will also lead to early failing of the generator bearing. For this reason, wind power plant operators need speciality lubricants that perform reliably, protect components and provide extended maintenance intervals.

Grease Is The Word

The maintenance of generators is an arduous task and is usually only performed when absolutely necessary. It can take 24 working hours to replace the bearings, on top of the loss in energy production, but all this can be avoided by cleaning the generator bearings with a special grease, then switching to a newly developed generator grease, which will protect the generator bearing in the future.

Conventional cleaning oils do not fully remove grease deposits and require the turbine to be shut down for cleaning. The Klübersynth BZ 68-400 cleaning grease contains special cleaning particles that remove residue from rolling bearings. It offers good protection against wear and corrosion, and more importantly, cleaning of rolling bearings can be done while the turbine is in full operation mode. This advanced cleaning grease is proven to reduce temperature shutdowns to almost zero and is compatible with other base oils for maximum versatility.

Maximise Efficiency, Minimise Maintenance

Klübersynth BZ 68-400 is designed for use prior to lubricant change in generator bearings for wind turbines. The product is easy to handle, decreases bearing temperature removes old, hardened grease deposits and extends bearing life.

The procedure for cleaning a bearing and removing the old deposits is simple: inject the cleaning grease, let it idle overnight and purge it out with the new generator grease the next day. Klübersynth BZ 68-400 comes in easy-to-use packages and can be applied manually with a grease pump or via an automatic lubrication system.

The four-step cleaning grease procedure is easy. The first step is to prepare: this means checking the bearing for failure and bringing bearings to operational temperatures. The second step is to clean: this stage involves disconnecting the bearing grease return pipe, pumping the cleaning product into the bearing while rotating the generator and then letting the turbine run overnight. Step three is to purge: this means purging the cleaning grease out of the bearing using Klüberplex BEM 34 – 131 N and ensuring the grease runs through the bearing until it is coming out of the outlet. The final step is operation: this means cleaning and reconnecting the grease return pipe, then the turbine is ready to be put back into operation.

Once the generator bearing has been cleaned, the operator can then use a high-performance generator grease to reduce generator bearing temperature alarm shutdowns by nearly 90% and increases the life of the bearing.

Klüberplex BEM 34-131 N is a special lubricating grease that combines excellent corrosion and wear protection with notably reduced frictional resistance in adverse environments and challenging working conditions.

Taking The Turbulence Out Of Turbines

For the smooth operation of wind-turbine power generation plants, the selection of the right lubricant is critical to ensure the maintenance of components and reliability of a wind farm. Klüber Lubrication has a history of innovation and technical support that contributes to reliable turbine operation. Working alongside wind energy service providers, key OEMs and operators, the firm delivers high-performance products that mean less lubricant is required, maintenance costs are reduced, operational hours are extended, and profits from turbines are maximised.